How to manipulate the array in Java?

Question

Starting with a 1-indexed array of zeros and a list of operations, for each operation, I have to add value to each of the array elements between two given indices, inclusive. Once all operations have been performed, I have to return the maximum value in the array. But the wrong answer is coming every time for most test cases and for some test cases time limit is exceeding. Kindly help me to solve this problem.

I am using arrayManipulation function to get the number of array elements and queries array. And update function is used to update(add the element) the array.

import java.util.*;
import java.util.Arrays;
public class sample
{
public static void main(String args[])
{
    int maximum=0;
    Scanner sc=new Scanner(System.in);
    int n=sc.nextInt();
    int m=sc.nextInt();
    int queries[][]=new int[m][3];
    for(int x=0;x<m;x++)
    {
        for(int y=0;y<3;y++)
        {
            queries[x][y]=sc.nextInt();
        }
    }
    maximum=arrayManipulation(n,queries);
    System.out.println(maximum);

}
public static int arrayManipulation(int num,int qry[][])
{
    int a=0,b=0,k=0;
    int max=Integer.MIN_VALUE;
    int arr[]=new int[num];
    int arr2[]=new int[num];
    for(int i=0;i<num;i++)
    {
         arr[i]=0;
    }
    for(int j=0;j<qry.length;j++)
    {
        for(int kl=0;kl<qry[0].length;kl++)
        {
            a=qry[j][kl];
            b=qry[j][kl+1];
            k=qry[j][kl+2];
            break;
        }
       arr2=update(a,b,k,arr);
       int lengtharr2=arr2.length;
       max=Math.max(max,arr2[lengtharr2-1]);
    }
    return max;
}

public static int[] update(int a1,int b1, int k1,int array[])
{

    for(int i=a1;i<b1;i++)
    {
        array[i]+=k1;
    }
    Arrays.sort(array);
    return array;
}
}

Input: 10 means the number of array elements and 3 is no. of queries which consist of a,b,k values which mean like this: the left index, right index, and summand

10 3

1 5 3

4 8 7

6 9 1

My output:

11

expected output:

10

Where is the line of code that prints any output? I don't see any prints in the included code — Tyler
– Tyler, Commented Nov 4, 2019 at 17:02
Well, you don't write to stdout. I would expect a line like System.out.println(something); Instead you ignore the result of the arrayManipulation method. Try something along the lines of: int output = arrayManipulation(n,queries); System.out.println(""+output ); — Lavandysh
– Lavandysh, Commented Nov 4, 2019 at 17:03
maximum=arrayManipulation(n,queries); System.out.println(maximum); — Divyanshu Sharma
– Divyanshu Sharma, Commented Nov 4, 2019 at 17:06
@ Lavandysh @Tyler after adding the above lines, the output for all the test cases are coming as 0 only. help me. — Divyanshu Sharma
– Divyanshu Sharma, Commented Nov 4, 2019 at 17:07
@DivyanshuSharma if you have already added those lines to your code but are still not getting any results, please update your question (you can click the 'edit' button near the bottom of the question — Gus
– Gus, Commented Nov 4, 2019 at 17:14

Anis R. · Accepted Answer · 2019-11-04 17:17:00Z

1

In this for loop:

for(int kl=0;k<qry[0].length;k++)
{
    a=qry[j][kl];
    b=qry[j][kl+1];
    k=qry[j][kl+2];
    break;
}

Why are you using two different variables (k and kl) in your loop condition?

Regardless, you should use a variable other thank k for the loop, as you are updating the value of k and then executing k++ at each iteration of your loop, which is very likely to mess up your output.

Consider something like:

for(int l=0;l<qry[0].length;l++)
{
    a=qry[j][kl];
    b=qry[j][kl+1];
    k=qry[j][kl+2];
    break;
}

answered Nov 4, 2019 at 17:17

Anis R.

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3 Comments

Divyanshu Sharma Over a year ago

I am not incrementing anything. k is the value passed to the function which is the summand to be add to the array and kl is the inner loop variable. I have edited the question kindly refer again and help me

Anis R. Over a year ago

@DivyanshuSharma so why are using k++ in your loop then? This increments k at each loop iteration.

Divyanshu Sharma Over a year ago

I am incrementing kl++ not k++

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